Therefore, the addition of RT in the adjuvant setting “should be considered” for locally advanced bladder cancer patients, Brian Baumann (Washington University in St Louis, Missouri, USA) and co-investigators remark.

Advertisement

The study included 120 patients aged 70 years and younger with one or more risk factors (≥pT3b, grade 3, or positive nodes) and negative margins after radical cystectomy plus pelvic lymph node dissection.

The researchers report in JAMA Surgery that after 2 years of treatment, locoregional recurrence-free survival (RFS) was significantly higher among the 75 patients randomly assigned to receive chemotherapy plus RT than among the 45 randomly assigned to receive chemotherapy alone, at 96% versus 69%.

“The magnitude of local control improvement with adjuvant RT arguably exceeds that reported for other cancers for which adjuvant RT is the standard of care, including breast, rectal, and vulvar cancer,” Baumann et al point out.

Furthermore, in an unplanned analysis of the 53.3% of patients with urothelial-only tumor histology, the 2-year locoregional RFS rate was significantly greater with chemotherapy plus RT (n=41) than with chemotherapy alone (n=23), at 100% versus 67%.

Advertisement

Disease-free survival and overall survival were also longer in the chemotherapy plus RT group than in the chemotherapy alone group, but not significantly so, at 68% versus 56% and 71% versus 60%, respectively.

After adjustment for potential confounders including age and tumor size, radiotherapy was associated with significantly reduced risks for locoregional recurrence (hazard ratio=0.08) but not with significantly reduced risks for disease recurrence or death.

Adverse event rates were generally higher among the patients who received RT than among those who did not, and there were five cases of late grade 3 gastrointestinal tract adverse effects in the former group compared with one case in the latter.

“While not definitive, these results suggest that patients with negative margins and locally advanced disease after [radical cystectomy] should be considered for referral to discuss adjuvant RT,” Baumann and co-authors conclude.

They add: “Phase 3 trials of adjuvant RT for patients with urothelial carcinoma are warranted.”

In an accompanying commentary, Cheryl Lee and colleagues from The Ohio State University in Columbus, USA, note that although the findings are “provocative,” aspects of the study design limit their interpretation.

These include the fact that it was a secondary phase II trial conducted in the setting of an ongoing phase III trial, concerns about time bias due to the chemotherapy only arm being added after the chemotherapy plus RT arm, and imbalances in age, tumor size, and number of resected lymph nodes between the two arms.

They also say that “it is uncertain how this regimen would be integrated into accepted treatment paradigms” that center around cisplatin-based neoadjuvant chemotherapy, but add that the results of three trials currently underway “are eagerly awaited and should help to elucidate the role of [adjuvant] RT in the current era for this patient population.”